Method of draining fluid from a transportable storage tank

ABSTRACT

A method of draining fluid from a self-supporting transportable storage tank having a rear wheel chassis, a rear drain fitting, and a jack assembly at the forward end of the storage tank is disclosed. The forward end of the storage tank is elevated by extending the jack assembly to lift the forward end thereof off the ground. The rear drain fitting is opened to allow fluid to drain from the storage tank. Alternatively, a front drain fitting may be provided, and the storage tank is drained by lowering the rear wheel chassis to lift the rear-end of the storage tank off of the ground, and opening the forward drain fitting.

This application is a divisional of application Ser. No. 08/819,041,filed on Mar. 17, 1997, U.S. Pat. No. 5,957,500, which was a divisionalof application Ser. No. 08/450,111, filed on May 25, 1995, U.S. Pat. No.5,653,469, the entire contents of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

tanks are currently provided for storing and dispensing fluids, such asfracturing liquids, drilling muds, and the like, for use at an oil orgas well site. Such tanks are also used to receive and hold fluids andchemicals at industrial plants. They are also used on environmentalclean-up jobs, as well as spills, to hold fluids until they can beproperly disposed of. When empty, these tanks are towed by truck fromone site to another, where they are refilled and reused. The tanksusually have lengths of 30 to 40 feet, a height of from approximately 9to 12 feet, and a width of 8 feet. Various federal, state and localhighway ordinances limit the size of these trailers for over-the-roadtransport. These tanks are constructed to have a large capacity, holdingthousands of gallons of liquid; therefore, there is a need to provide amobile storage tank constructed and arranged to not only increase thestorage capacity of the tank for holding fluids at the job site, butalso dimensioned to conform to the highway ordinances for over-the-roadtransport.

SUMMARY OF THE INVENTION

The mobile storage tank of the present invention is provided with aladder and manholes which are recessed into the walls of the tank sothat a maximum height of twelve feet, six inches, and a width of eightfeet, six inches can be obtained, and still be in conformance withhighway law regulating the size of trailers.

The storage tank is provided with a sloped bottom wall and a sidemanhole positioned so that a person, while standing on the ground, canhave access to the interior of the tank for the cleaning thereof.

The storage tank is also provided with a jack system and a king pin fora fifth wheel on the front thereof, and a rear wheel lift system, to notonly facilitate the towing of the empty tanks by a regular tractor, butalso to facilitate the draining of the tank, and provide a new method oftransporting and draining fluid from the tanks.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a side elevational view of the mobile storage tank of thepresent invention, with the rear wheels in the lowered position and thefront portion of the storage tank resting on the ground;

FIG. 2 is an elevational view of the side of the tank opposite to thatshown in FIG. 1, and showing the rear wheels in the elevated positionand the storage tank resting on the ground;

FIG. 3 is a top plan view of the storage tank;

FIG. 4 is an enlarged front elevational view of the storage tank;

FIG. 5 is a fragmentary, horizontal sectional view taken substantiallyalong line 5—5 of FIG. 1;

FIG. 6 is a fragmentary, cross-sectional view taken substantially alongline 6—6 of FIG. 1;

FIG. 7 is a rear elevational view of the mobile storage tank wheelchassis in the elevated position;

FIG. 8 is a fragmentary, side elevational view of the rear of thestorage tank, showing the tank resting on the ground when the rearwheels are in the elevated position;

FIG. 9 is a rear elevational view of the mobile storage tank wheelchassis in the lowered position;

FIG. 10 is a fragmentary, side elevational view of the storage tankshowing the rear of the tank in the elevated position above the groundwhen the rear wheels are in the lowered position;

FIG. 11 is a view taken substantially along line 11—11 of FIG. 10illustrating the extension and retraction mechanism for lowering andraising the rear wheel chassis;

FIG. 12 is a side elevational view of one of the latching devicesemployed in the extension and retraction mechanism shown in FIG. 11;

FIGS. 13, 14, 15 and 16 are side elevational views illustrating thesequential steps of attaching the mobile storage tank to a tractor fortransport; and

FIG. 17 is a side elevational view of a pair of tandem mobile storagetanks connected to a tractor.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings in greater detail, and more particularly toFIGS. 1, 2 and 3, the mobile storage tank of the present inventioncomprises, an elongated enclosure having a front or forward end 1, arear end 2, a pair of opposed, vertically extending side walls 3 and 4,a top wall 5, bottom wall 6 at the rear end, and a bottom wall 7 at theforward end. The bottom walls 6 and 7 are sloped downwardly toward adownwardly curved bottom wall 8 intermediate the bottom walls 6 and 7,with a rearwardly extending drain fitting 8 a communicating with theinner bottom of the bottom wall 8.

As will be seen in FIGS. 3, 4 and 5, a recess 9 is provided in a cornerof the tank at the forward end 1 inside wall 3 for accommodating aladder 10 to facilitate access to the tank top wall 5 and manhole 11mounted therein. It is to be understood that recess 9 can be provided inany corner of the tank but the forward right corner in which it is shownis the preferred position. The recess is formed by bottom wall 9′extending diagonally between, and connected at its ends to, top wall 5and external portion 7′ of forward bottom wall 7. The side edges ofdiagonally extending bottom wall 9′ are connected by welding tocorresponding diagonal edges of side wall 3 and recessed side wallportion 3′. The ladder 10 is connected to the diagonal or downwardly andforwardly sloping bottom wall 9′ by stand-off elements 10′.

Similarly, recesses 12, 13 and 14 are provided in the forward end 1,side wall 3 and rear end 2′ for housing manholes 15, 16 and fitting 17(FIGS. 6 and 7), respectively. By recessing the ladder 10, manholes 15and 16, and fitting 17 within their respective walls a maximumvolumetric dimension can be obtained for the storage tank while stillconforming to highway laws regulating the size of trailers.

Furthermore, the manholes 15 and 16 are positioned at a predeterminedheight so that a person, while standing on the ground, when the tank ison the ground, can have access with his head, shoulder and arms to theinterior of the tank for the cleaning thereof. The draining and cleaningof the tank is further facilitated by the sloped bottom walls 6 and 7communicating with the longitudinally extending curved bottom wall 8which, in turn, communicates at the rear end thereof with a laterallyand downwardly extending conduit 18 having a hinged cover 19. Thearcuately curved bottom wall 8 also communicates at the rear end thereofwith the rearwardly extending centrally located drain fitting 8 a, andat the front end thereof with the forwardly extending centrally locateddrain fitting 8 b. These three drains provide the operator versatilityin cleaning and draining the tank according to its position relative towhere the fluid being drained must be directed. The rearwardly extendingdrain fitting 8 a is connected on vertical rear end wall 6′ thatconnects rear sloped bottom wall 6 to curved bottom wall 8, whileforwardly extending drain fitting 8 b is connected on vertical front endwall 7″ that connects forward end sloped bottom wall 7 to curved bottomwall 8.

As will be seen in FIGS. 4 and 6, the curved bottom 8 having therearwardly extending drain fitting 8 a and forwardly extending drainfitting 8 b, is supported by cradle members 20 connected between thecurved bottom 8 and a flat, reinforced floor 21 constructed oflongitudinally and laterally extending channel members, providing a skidfor supporting the tank on the ground 22, as shown in FIGS. 2 and 13.The tank can also be supported on the ground by a pair of laterallyspaced, telescopic jacks 23 which can be either manually actuated orfluid actuated, the jacks 23 being connected to the tank adjacentopposite sides and adjacent the rearwardly extending end of slopedbottom wall 7, and in front of vertical front end wall 7″, as shown inFIGS. 1, 2 and 4. The telescopic jacks 23 have a retracted length suchthat in the retracted position, as shown in FIGS. 1, 2 and 4, the topends are adjacent the bottom of front bottom wall 7, and the bottom endsare adjacent the bottom of reinforced floor 21 and the ground, thusextending the height of reinforced floor 21 and front end wall 7″. Aking pin 24 is connected to the bottom wall 7 for connection to thefifth wheel of a tractor to be described more fully hereinafter.

Referring to FIGS. 7 to 10, the rear of the storage tank is supported bya rear wheel chassis 25 including an axle 26 connected to the medialportion of a leaf spring 27 having its outer ends connected to springhangers or brackets 28 and 29. While bracket 28 is fixedly connected tothe bottom wall 6 of the storage tank, the bracket 29 is mounted to theouter end of a cross beam 30, as shown in FIG. 11.

A fluid motor 31, including a cylinder 32 connected to the bottom wall 6and a piston rod 33 connected to the cross beam 30, is provided eitherfor raising the cross beam 30 and associated wheel chassis 25, tothereby lower the storage tank to rest on the ground, as shown in FIG.8, or for lowering the wheel chassis 25 to lift the storage tank off theground, as shown in FIGS. 10 and 11.

The reciprocatory movement of the cross beam 30 is guided by a pair ofspaced, parallel, vertically extending tubes 34 having their lower endportions integral with the cross beam 30, and their upper end portionstelescopically received in tubular members 35 integral with the bottomwall 6 of the storage tank, and protruding through the bottom wall tothe inside of the storage tank, as shown in FIGS. 6 and 11. In order tohold the guide tubes 34 in the extended position, while the wheelchassis 25 is in the lowered position, a latch assembly 36 is providedfor each telescopic tube 34. Each latch assembly 36 comprises a plate 37pivotally connected as at 38, by a pivot rod welded on one end, to thelower end of movable tube 34. The free end of plate 37 is provided withan apertured flange 39 having a boss 40. A similar apertured flange 41is fixedly attached to the lower end of tubular member 35 by a bracket42. To hold the tube 34 in the extended position, the plate 37 ispivoted upwardly, as shown in FIG. 12, so that the boss 40 abuts andaligns with the apertured flange 41, and a latch pin 43 is insertedthrough the flange 41, boss 40, and flange 39.

FIGS. 13 to 16 illustrate the method by which an empty storage tank istransported from one site to another. As will be seen in FIG. 13, thestorage tank is resting on the ground and a tractor 44 is backed intoposition so that the fifth wheel 45 on the tractor 44 is aligned withthe king pin 24 on the storage tank. Suitable pneumatic and/or hydraulichoses 46 are then connected between the storage tank and the tractor 44to use the pressurized system on the tractor to pressurize the pneumaticand/or hydraulic system, not shown, on the storage tank. The jacks 23are then extended, as shown in FIG. 14, to lift the front of the storagetank a sufficient distance to allow the tractor 44 to back into thefront of the storage tank to lock the fifth wheel 45 to the king pin 24,as shown in FIG. 15, while the brakes on the rear wheel chassis areapplied. The fluid motor 31 is then actuated to lower the rear wheelchassis 25, to thereby lift the rear of the storage tank off the ground,as shown in FIG. 16, and the jacks 23 are retracted and the latchassemblies 36 are manipulated, and the latch pins 43 inserted, to holdthe wheel chassis 25 in the lowered position.

After the tank is transported to its new site it is deposited on theground at the new site using the reverse method described, except thatafter the rear wheel chassis is raised to lower the rear end of thestorage toward the ground, the jacks 23 are then extended to the groundto support the forward end of the storage tank above the ground. Theking pin 24 is then disconnected from the fifth wheel 45 of the tractor44 by moving the tractor out from under the king pin 24. The jacks 23are then retracted lowering the reinforced floor 21 of the storage tankonto the ground. It is to be understood that in this method of loweringthe tank onto the ground, the jacks 23 can first be extended intocontact with the ground and thereafter the rear wheel chassis can beraised to lower the rear end of the tank, or these steps can beconducted simultaneously, followed by the steps of disconnecting theking pin from the tractor, and then lowering the tank onto the ground byretracting the extended jacks 23.

While one storage tank can be transported, as shown in FIGS. 13 to 16, apair, or more, of storage tanks can be transported in tandem, as shownin FIG. 17, wherein the second storage tank is connected to the rear endof the first storage tank by a conventional trailing dolly 47 having afifth wheel 48 connected to the king pin on the second trailer and atongue 49 connected to a hitch 50 on the rear of the first trailer.

While the manipulation of the jacks 23 and wheel chassis 25 has beendescribed with regard to the connection of the storage tank to atractor, it will be appreciated by those skilled in the art that themovement of the jacks 23 and wheel chassis 25 can also be employed fortilting the storage tank so that the tank can be fully drained throughthe fittings 8 a and 8 b and the laterally extending conduit 18 duringthe cleaning of the tank, which cleaning is further facilitated by themanholes 15 and 16 being positioned at a predetermined height above theground to allow a person standing on the ground to have access to theinterior of the tank with his head, shoulders, arms, and a hose forhosing down the interior.

The storage tank has a pair of pressurized pneumatic tanks, not shownfor sake of clarity, for pressurizing the pneumatic and/or hydraulicsystems on the storage tank. These pressurized pneumatic tanks arepreferably located above the rear wheel chassis 25, below rear bottomwall 6, and between fluid motor 31 and rear end wall 6′. Thispressurized pneumatic source is connected into the brake system of therear wheel chassis as a safety feature, and can be used in the newmethod of cleaning the tank, or the pressurized system of the tractorcan be used by connecting the hoses 46 from the tractor to the tanksystem. Which pressurized source will be used in the cleaning methodwill depend upon the orientation of the tank at the site relative to aholding pond or the like for the waste cleaning water from the tank, andif a tractor can be placed adjacent the tank.

If, for instance, the waste fluid holding pond is in front of the tank,the waste water from cleaning will be drained from the storage tankthrough forwardly extending drain fitting 8 b. With the tank on theground using side manhole 16, and/or front manhole 15, the cleaner canbend to place his head, shoulders, arms and the nozzle of a cleaninghose inside the tank during a hose-down cleaning operation. Since rearbottom wall 6 and front bottom wall 7 slope downwardly toward thedownwardly curved side bottom wall 8, all of the waste cleaning fluiddrains down to the bottom wall 8. With a drain hose attached toforwardly extending drain fitting 8 b fluid motor 31 is actuated tolower the rear wheel chassis 25, as shown in FIG. 1, to thereby lift therear of the storage tank off the ground, while the front of the storagetank is still on the ground, causing the waste cleaning water to beexpelled through forward drain fitting 8 b which is then at thelowermost point of the storage tank.

If, for instance, the waste fluid holding pond is in back of the storagetank, the waste water from cleaning will be drained from the storagetank, in a similar manner, either through rearwardly extending drainfitting 8 a or side conduit 18 and cover 19. With the rear wheel chassis25 raised, and its brakes applied, the pair of jacks 23 are extended tothereby lift the front of the storage tank off the ground to the pointas shown in FIG. 14, causing the waste cleaning water to drain to therear of the tank and be expelled through rearward drain fitting 8 aand/or side conduit 18 and manhole cover 19, which are then at thelowermost point of the storage tank.

The terms and expressions which have been employed herein are used asterms of description and not of limitation, and there is no intention,in the use of such terms and expressions, of excluding any equivalentsof the features shown and described or portions thereof, but it isrecognized that various modifications are possible within the scope ofthe invention claimed.

I claim:
 1. A method of draining fluid from a self-supporting,transportable storage tank having a rear wheel chassis and a rear drainfitting at the rearward end of the storage tank, and a jack assembly anddrain fitting at the forward end of the storage tank, comprising thesteps of: a) lowering the rear wheel chassis to lift the rear end of thestorage tank off the ground, and b) opening the forward drain fitting toallow fluid to drain from the tank therethrough.
 2. The method of claim1, comprising the additional steps of: c) closing the forward drainfitting; d) raising the rear wheel chassis to lower the rear end of thestorage tank against the ground; e) raising the forward end of thestorage tank off the ground by extending the jack assembly against theground; and f) opening the rear drain fitting to allow fluid from thetank to flow therethrough.